1. Field of Invention
This invention generally relates to valves for inflatable objects, specifically to a novel modification to conventional check valves and its methods of use for the purpose of improving the stability and style of inflatable objects.
2. Prior Art
Inflatable products are typically fashioned from flexible polymer materials such as polyvinylchloride. As the strength of flexible polymer materials has improved, more inflatable products, including inflatable furniture, have become available. Inflatable products can be large, light, attractive and cheap; they can be readily inflated and used or deflated and stored in very small spaces; and they can be easily cleaned.
Inflatable objects are generally somewhat balloon-like. Their stiffness and bounciness depend partly on their level of inflation and their configuration. While the shapes of their component sheet elements and their internal structures establish their overall shapes or contours, inflatable objects, when inflated, tend to have surfaces that bulge outwards. Furthermore, because the air inside inflatable objects is substantially movable and compressible, external pressure can easily distort their shapes by forcing the air in edge or corner regions to flow away and redistribute. This causes inflatable objects to be structurally unstable when used as support systems such as furniture. For example, when weight is applied at an edge of an inflatable chair, the side of the chair tends to distort. Such a distortion can cause a person to slip from the seating surface, increasing the person's risk of injury. This problem becomes more significant as the height of the support system increases.
In the prior art, this problem was addressed by employing extra stabilizing and reinforcing tubes or independent chambers, as taught in U.S. Pat. No. 5,947,563 (1999), U.S. Pat. No. 6,089,668 (2000), U.S. Pat. No. 6,152,530 (2000), U.S. Pat. No. 6,161,902 (2000), U.S. Pat. No. 6,328,385B1 (2001) and U.S. Pat. No. 6,671,910B2 (2004). However, these tubes or chambers need to be inflated through multiple external conventional valves. Unfortunately, the extra valves may cause poor air retention if cheap conventional valves are used, as usually do, in such applications as inflatable furniture. Yet some designs also require manual assembly of independent parts. Furthermore, a single built-in pump cannot work without a complex air distribution system. To enable the use of a single built-in pump, U.S. Pat. No. 6,996,867B2 (2006) proposed a different approach for an air mattress. The stabilizing and reinforcing components of the air mattress are only in fluid communication with the main chamber through small air passages or holes. The size and configuration of such passages can slow air flowing out of the stabilizing and reinforcing chambers and, therefore, increase the mattress' stability. However, since the air loss can only be slowed rather than eliminated, the design cannot provide stability under constant pressures or forces. Furthermore, all of the chambers in the design have the same air pressure although it can be desirable to have a higher pressure in the stabilizing or reinforcing chambers for stability and a lower pressure in the main support chamber for comfort. In all the approaches described above, stabilizing or reinforcing parts most likely add additional profiles that can make inflatable products less attractive.
Conventional check or one-way valves and their methods of use are well known in the prior art. They basically have no means of discharging air and are used internally in fluid control systems or air pump systems of inflatable mattresses, as taught in U.S. Pat. No. 2,997,100 (1961), U.S. Pat. No. 3,583,008 (1971), U.S. Pat. No. 3,978,530 (1976), U.S. Pat. No. 5,794,288 (1998), U.S. Pat. No. 6,196,260B1 (2001) and U.S. Pat. No. 6,418,579B2 (2002). The check valves in these applications prevent air from flowing back to main chambers but the air can still escape through other passages or by other discharging means. Check valves are also used externally with standard valves for inflatable objects, when being integrated at the inner end of the tube of the external valves, as taught in U.S. Pat. No. 2,839,073 (1958). In this case discharging can be done with direct external interventions, such as insertion of a slender rod from outside, to open the check valves.
The use of conventional check valves presented in U.S. Pat. No. 4,541,135 (1985) should also be noted. As in the prior art described above, a separate inflatable tube is employed around the side of an air mattress and, when inflated, provides support for the mattress. The air mattress and the tube are inflated also through separate external valves. The support tube is further divided into one main chamber and two or four independent sub-chambers to increase its stability while still to be inflated through one external valve. The air forced through the external valve of the tube into the main chamber inflates these sub-chambers individually and simultaneously through four conventional check valves that are installed internally and close to the external valve. However, unlike the chambers described in the prior art, these sub-chambers may have no other air passages or discharging means. Unfortunately, to deflate the sub-chambers, one must insert a long instrument through the external valve to open each of the check valves.
Thus, it is desirable in the art to have a simple device that:                (a) can improve the structural stability of inflatable objects without changing their basic designs;        (b) can be invisible from the outside of inflatable objects;        (c) can be installed at any desired location inside inflatable objects;        (d) can enable inflatable objects to be conveniently inflated by one standard built-in pump;        (e) can avoid the poor air retention of extra external valves;        (f) can enable inflatable objects to have internal partitions with different pressures;        (g) can function without external instruments; and        (h) can significantly reduce the roundness of inflatable objects' edges and corners.        
Accordingly, these are the objects and advantages of the present invention. Further objects and advantages will become apparent after consideration of the following detailed description and drawings.